Herbicidal compositions comprising haloaryloxy substituted aliphatic acids



HERBICIDAL COMPOSITIONS COMPRISING EATiIggARYLOXY SUBSTITUTED ALIPHA'I'IC.

Henry L. Merrill,v Clayton, Mo-., assignor to Monsanto Chemicai Company, ShLouis, Mo., a, corporation of Delaware N Drawing; Application May 7, 1951,

Serial! No- 22 42: 21Claims. '(Cli vi -2 .4

This invention relates to'herbicidal compositions comprising haloaryloxy substituted aliphatic acids and particularly to methods for preparing same- The invention cidal properties in order to produce dry formulations for the control of noxious vegetation. However, certain disadvantages still remain. One disadvantage isthat the haloaryloxy aliphatic acids are usually incorporated eitherin the solid carrier followed by a turnblingoperation or as a part of a grinding operation in a pebble mill for reducing the componentparts to the appropriate particle size. These operationsareexpensive and time consuming and produce a productcontaining 1a large amount of fines. Such haloaryloxy aliphatic acid con taining formulations are objectionable in that when the dry formulation is applied, for example by a manually or automatically operable duster, these finely divided particles or fines float in'the air and via air currents. are apt to come in contact with and injure orv destroy desirable vegetation. These finely divided particles or fines are objectionable not only in view of the aforesaid but also because they represent aflwaste of material.

in accordance with this invention it has been found that the above objections are 'substantially overcome without in any way impairing the value of the materials as herbicides by the fusion of a solid absorbent material with a haloaryloxysubstituted aliphatic acid of the formula where X is a halogen atom, where n isa whole number, where R is an aryl radical, and. where R-COOH is an aliphatic acid residue. The fused product is a highly effective substantially dustless herbicidal composition which embodies an optimum distribution of the haloaryloxy aliphatic acid throughout the resultant composition. In this fused form the composition has a far greater herbicidal effect over a longer period of time than other forms of. herbicidal compositions containing a haloaryloxy aliphatic acid. The herbicidal composi tion of this invention not only exhibits much better last.- ing properties but withstands. a far greater amount of rainfall than do other forms of compositions containing a haloaryloxy aliphatic acid. In view of the long lastnited States Patent i be herbicidally active or inert. Exemplary of such 'are 'fullers earth, kieselguhr, diatomaceous earth, talc, chalk,

wood flour, nutshell flours, charcoal, inorganic, phosphates, magnesium carbonate and like solid materials. which are absorbents for the haloaryloxy aliphatic acids. In carrying, out the process of this, invention the solid carriers should have a particle size.

of this invention.

of less than about microns and preferably less than about 15 microns. It is to be emphasized that the. car: rier is not just coated but that the haloaryloxy aliphatic acid is. absorbed in the porous carrier.

tetrachlorophenoxyacetic acid; pentachlorophenoxyacetic acid; vp -bromophenoxyacetic acid; 2,4.-dibromophenoxy'- acetic acid; 2,4,o-tribrom'ophenoxyacetic acid; p-iod'ophenoxyacetic acid; p-fiuorophenoxyacetic acid; 2,4 -difiuorophenoxyacetic acid; 4-chloro-o-toloxyacetic acid;

4-chloro-m-toloxyacetic acid; 4-chlo-ro-2-ethylphenoxyacetic acid; 4-chloro-3,5dimethylphenoxyacetic acid; 2- chloro-I-naphthoxyacetic acid; 2,4-dichl'oro-l-naphthoxy-- acetic acid; a[ 2-chloro-1-naphthoxy1-propionic acid and the corresponding haloaryloxy derivatives of higher aliphatic acids andthe'corresponding haloaryloxy deriva-,'

tives of such unsaturated aliphatic acids as acrylic acid and its homologues;

In carrying out the. process of this invention either crude or pure haloaryloxy substituted aliphatic acid can be employed and it is preferred that the crude or pure acid be added in the form of a melt to a solid absorbent ing properties and resistance. to Washing, ofii via rainfall v the herbicidal compositions. of this invention aiford the application of larger amounts of herbicide per unit area,

thus reducing the number of applications per unit time. Furthermore the fused products are characterized by good storage properties in that they exhibit no tendency to cake or to produce fines by the rubbing of the fused particles. against one another.

The. solidabsorbent: materials employed: inthe formation; of the herbicidal-compositions of: this invention may carrier which is being. agitated in a suitable mi'xing apparatus, the temperature of the'carrier during the addi;

tion of the melt being above the fusion temperature of the crude orpure acid but below the decompositiontemperature of the particular acid. However, in the broader aspects of this invention it is to be understood/that variations of the aforesaid can be employed. For example, the crude or pure acid and solid absorbent carrier may be first mechanically mixed and then heated to a temperature above the fusion temperature of the crude or pure acid, or the acid may be added in, solid form to the solidabsorbent carrier, the latter being heated sufliciently during the addition such that the temperature of the mix does not fall below the fusion temperature of the crude or pure acid.

As an example of the preferred embodiment of this invention the following is illustrative:

Example I 200 parts by weight of fullers earth (l-20 microns) is charged into a suitable vessel and heated to above 150 C. Thereupon, while rotating the vessel and maintaining the temperature at about 1 55= (3., there is added 22.2 parts by weight of molten 2,4-dichlorophenoxyacetic acid (M. P. 138 C.) Upon completion of the acid addition the vessel is. rotated for a few minutes while maintaining the temperature atabout 145 -155 C. andthen cooled. The resultant product is substantially dustl'ess' andcomposcd of discrete particles containing 10%. by weight of 2,4-di'chlorophenoxyacetic acid dispersed. therein.

.Upon evaluating the herbicidal composition of Example I against'a herbicidal composition containing the same rato of active ingredient to carrier but mixed mechanically by conventional methods, by the application of each, respectively, to an area infested with noxious vegetation at the same ratio-of active ingredient per unit. area it is found that the former composition withstands one and one-half to two times as much rainfall as the. latter andis one. and one-half to two times as effective Patented Mar. 20,;1956

in length of time of controlling the growth of noxious vegetation. V

As further examples of the preferred embodiment of this invention, the following is illustrative:

Example I I 100 parts by weight of talc (1-7 microns) is charged into a suitable vessel and heated to about 120 C. Thereupon, while rotating the vessel and maintaining the temperature at about 1l5-125 C., there is added 11.1 parts by weight of molten 4-chloro-o-toloxyacctic acid (M. P. 118 C.). Upon completion of the acid addition the vessel is rotated for a few minutes while maintaining the temperature at about l15-125 C. and then cooled. The product so formed is substantially dustless and composed of discrete particles containing by weight of 4-chloro-o-toloxyacetic acid dispersed therein.

Employing a technical grade of 4-chlor0-o-toloxyacetic acid having a melting point of 97-105" C., the operating temperature is reduced from 1 125 C. to 95-110 C. The substantially dustless product resulting thereby is not unlike that obtained by the usage of pure 4-chloroo-toloxyacetic acid.

Example III 500 parts by weight of cclite lmicrons) is charged into a suitable vessel and heated to about 165 C. Thereupon, while rotating the vessel and maintaining the temperature at about 160-170 C., there is added 22.2 parts by weight of molten 2,4,S-trichlorophenoxyacetic acid (M. P. 160 C.). Upon completion of the acid addition the vessel is rotated for a few minutes while maintaining thetemperature at about 160170 C. and then cooled. The product so formed is substantially dustless and composed of discrete particles containing 4.25% by weight of 2,4,S-trichlorophenoxyacetic acid dispersed therein.

Upon evaluating the respective compositions of Examples ll, and III against anhydrous herbicidal compositions containing, respectively, the same ratio of ingredients mechanically mixed by conventional methods there is obtained in each instance substantially the same relativeresults as in Example I.

In another aspect the process of this invention embodies the inclusion of small amounts of additives, e. g. 110% by weight based upon the acid of additives such as dimethylamine, triethylamine, diethanolarnine, triethanolamine, isopropylamine, isopropanolamine, glycerol, glycols, sodium or potassium ethyl phosphates, polyvinyl alcohol, gelatin, methyl cellulose, sodium carboxymethyl cellulose and the like. Such additives may be incorporated directly or in the form of aqueous solutions either before or after the fusion operation. While such additives are not necessary in the preparation of the herbicidal compositions of this invention their admixture with the acid prior to the fusion operation results in a lowering of the fusing temperature below that of the melting point of the crude or pure acid. As an example of this embodiment the following is illustrative:

Example I V 496 parts by weight of fullers earth (10-40 microns) is charged into a suitable vessel and heated to about 115 C. Thereupon while rotating the vessel and maintaining the temperature at about 115 C., a melt of a herbicidal mixture containing 55.5 parts by Weight of 2.4-dichlorophenoxyacetic acid, 4.2 parts by weight of triethanolamine, and 10 parts by weight of water is incorporated therein. Upon completion of said addition the vessel is rotated for S-lOminutes at 110-120" C. to remove all of the water and subsequently cooled. The resultant product is substantially dustless and composed of discrete particles containing 10% by weight of 2,4-dichlorophenoxyacetic acid dispersed therein.

As another example of the process of this invention in its broader aspects the following is illustrative:

Example V 494 parts by weight of diatomaceous earth (10-40 microns) and 55.5 parts by weight of 2,4-dichlorophcnoxyacetic acid is charged into a suitable vessel and while rotating the mix is heated to 150 C. for 5-10 minutes. The melt is cooled to about C. and thereto is added and intimately mixed 55 parts by weight of a 10% by weight aqueous solution of gelatin. The mix is then held at 1 10-120% to remove the water. The resultant product obtained upon cooling the mix is substantially dustless and composed of discrete particles containing 10% by weight of 2,4-dich1orophenoxyacetic acid dispersed therein. V

The haloaryloxy substituted aliphatic acids of this invention can be admixed withthe absorbent carrier in any suitable herbicidal quantity as for example amounts up to about one part acid for each part of carrier. In that the process of this invention is particularly concerned with the manufacture of concentrated herbicidal compositions the quantity of active ingredient will ordinarily be maintained at the maximum consistent with the absorptivity of the carrier.

While this invention has been described relative to certain specific embodiments it is not so limited but that modifications and variations thereof obvious to those skilled in the art may be made without departing from the spirit or scope of the invention.

What is claimed is:

1., The method of preparing a free-flowing discrete particulate substantially dustfree herbicidal composition which consists in mixing a herbicidal mixture comprising a haloaryloxy substituted. aliphatic acid with a finely divided solid absorbent carrier therefor wherein the weight 7 of the haloaryloxy substituted aliphatic acid does not exceed the weight of the solid absorbent carrier, subjecting the mixture While agitating to a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained. t

2. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding a haloaryloxy substituted aliphatic acid to a finely divided solid absorbent carrier therefor while maintaining the temperature of the carrier above the fusion temperature of the acid, the weight of the said acid being not greater than the weight of the solid absorbent carrier, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the freeflowing discrete particulate substantially dust-free herbicidal composition is obtained.

3. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding a haloaryloxy substituted acetic acid in the form of a melt to a finely divided solid absorbent carrier therefor While maintaining the temperature of the carrier above the fusion temperature of the acid, the weight of the said acid being not greater than the weight of the solid absorbent carrier, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained.

4. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding a halophenoxy substituted acetic acid in the form of a melt to a finely divided solid absorbent carrier therefor while maintaining the temperature of the carrier above the fusion temperature of the acid, the Weight of the said acid being not greater than the weight of the solid absorbent carrier, agitating the resulting mixture at atemperature above the fusion temperature of the said acid, cooling the resultant mixture whereby the freeflowing discrete particulate substantially dust-free herbicidal composition is obtained.

5. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding a chlorophenoxy substituted acctic acid in the form of a melt to a finely divided solid absorbent carrier therefor while maintaining the tempera ture of the carrier above the fusion temperature of the acid, the weight of the said acid being not greater than the weight of the said solid absorbent carrier, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the .resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained.

6. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding a chlorophenoxy substituted acetic acid in the form of a melt to fullers earth while maintaining the temperature of the fullers earth above the fusion temperature of the acid, the weight of the said acid being not greater than the weight of the said fullers earth,

agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is ob tained.

7. The method of preparing a free-flowing discrete par ticulate substantially dust-free herbicidal composition which consists in adding 2,4-dichlorophenoxy acetic acid in the form of a melt to fullers earth while maintaining the temperature of the fullers earth above the fusion temperature of theacid, the weight of the said acid being not greater than the weight of the said fullers earth, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained.

8. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding 2,4,5-trichlorophenoxy acetic acid in the form of a melt to fullers earth while maintaining the temperature of the fullers earth above the fusion temperature of the acid, the Weight of the said acid being not greater than the weight of the said fullers earth, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the resultant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained.

9. The method of preparing a free-flowing discrete particulate substantially dust-free herbicidal composition which consists in adding 4-chloro-o-toloxy acetic acid in the form of a melt to fullers earth while maintaining the temperature of the fullers earth above the fusion temperature of the acid, the weight of the said acid being not greater than the weight of the said fullers earth, agitating the resulting mixture at a temperature above the fusion temperature of the said acid, and cooling the result-- ant mixture whereby the free-flowing discrete particulate substantially dust-free herbicidal composition is obtained.

.1 0. A herbicidal composition prepared according to the 7 process of claim 9.

16. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the composition of claim 10.

17. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the composition of claim 11.

18. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the'composition of claim 12.

19. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the composition of. claim 13.

20. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the composition of claim 14. I

21. A process of controlling noxious vegetation which comprises treating noxious vegetation over a prolonged period of time with a herbicidal quantity of the composition of claim 15.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,443 Heath Apr. 7, 1942 2,322,761 Lontz June 29, 1943 2,390,941 Jones Dec. 11, 1945 2,423,457 Lynn July 8, 1947 2,523,228 Mullison Sept. 19, 1950 2,529,681 Flenner Nov. 14, 1950 2,529,682 Flenner Nov. 14, 1950 FOREIGN PATENTS 7 366,705 Italy Jan. 5, 1939 

1. THE METHOD OF PREPARING A FREE-FLOWING DISCRETE PARTICULATE SUBSTANTIALLY DUST-FREE HERBICIDAL COMPOSITION WHICH CONSISTS IN MIXING A HERBICIDAL COMPOSITION A HALOARYLOXY SUBSTITUTED ALIPHATIC ACID WITH A FINELY DIVIDED SOLID ABSORBENT CARRIER THEREFOR WHEREIN THE WEIGHT OF THE HALOARYLOXY SUBSTITUTED ALIPHATIC ACID DOES NOT EXCEED THE WEIGHT OF THE SOLID ABSORBENT CARRIER, SUBJECTING THE MIXTURE WHILE AGITATING TO A TEMPERATURE ABOVE THE FUSION TEMPERATURE OF THE SAID ACID, AND COOLING THE RESULTANT MIXTURE WHEREBY THE FREE-FLOWING DISCRETE PARTICULATE SUBSTANTIALLY DUST-FREE HERBICIDAL COMPOSITION IS OBTAINED. 